PARK CITY – For her feature directing debut, screenwriter Liz W. Garcia pegs her semi-comedic storyline to a wafer-thin premise about a woman returning to her hometown and attempting to re-experience her adolescence in all the wrong ways. Although a slight, overly contrived film, The Lifeguard will nevertheless strike chords with young women approaching and contending with their 30s. Theatrical distributors will certainly come calling on the basis of Garcia’s credits and the film’s casting, but converting those elements into box office returns could prove challenging.

Leigh (Kristen Bell), 29 and mostly single, is an AP reporter who’s finding coverage of New York City metro news increasingly stressful, but it’s the revelation that her lover/editor/boss is getting married that prompts her to drop out of her job, return to her Connecticut hometown and move in with her parents, telling them “I just need some time out from my life,” much to their bemusement.

With a playbook that essentially consists of rewinding to her high-school years, Leigh gets a job as a lifeguard at the pool where she used to work back in the day, reunites with her BFFs – married Mel (Mamie Gummer) and closeted Todd (Martin Starr) -- and begins acting like a teenager again.

After meeting skater kid Jason (David Lambert), the sixteen-year-old son of the on-premises groundskeeper at the pool, Leigh and Todd convince him and his friends to buy them some pot and before you can say “kegger” the teens and adults are hanging out and partying together, propelled by Leigh’s youthful regression. Even straightlaced Mel, now the vice principal of their old high school, joins in.

Jason begins making his interest in Leigh fairly clear and they’re soon engaged in a torrid affair that essentially rewrites her personal history, replacing her virginal high-school years with a sexed-up reboot. Jason’s intent to drop out of classes and move to Vermont before the fall term starts forces Leigh to begin reconsidering her future as well, until an unexpected tragedy overturns everybody’s plans.

Surprisingly for a writer turned director, the most evident shortcomings with Garcia’s feature originate with the script. With barely any backstory to support them, the characters consistently appear to lack the motivations necessary for their actions. It seems highly implausible for adults with too much at stake and so little impetus other than getting high or getting laid to repeatedly engage in so much risky behavior with underage teens. Opportunities that could be better devoted to developing character or advancing the plot are squandered on repetitive montage sequences supported by forgettably lighthearted pop tunes.

As director, Garcia shows more decisiveness -- cinematography, coverage and editorial are all competently accomplished, but cast direction often wavers, unable to rise above the limitations of the script.

While Kristen Bell’s talent and charisma are clearly evident, she seems adrift with her character, since Leigh has no clear justification for abandoning her city life and career to return home, much less for initiating an affair with the teenage son of her coworker, clearly putting her newfound job at risk. Lambert manages a believable chemistry with Bell, but can’t summon the appropriate teen swagger for the remainder of the part -- the rest of the cast mostly serves to drive inconsequential subplots.

With this perhaps semi-autobiographical film in the can, Connecticut native Garcia may find more consequential alternatives for exercising her considerable talents.